The present invention relates to processing a web of fibers into thread and, more particularly, relates to dividing a nonwoven web into multiple continuous ribbons.
Yarn is a strand composed of fibers, filament, or other materials, either natural or man-made, suitable for use in the manufacture of fabrics. Most fiber processing operations are performed by mechanical means. Typically, natural fibers such as cotton, or man-made materials, are shipped in bales to a textile mill for yarn manufacturing. The traditional processing method involves subjecting the bail of cotton to opening and cleaning, picking, carding, combing, drawing and spinning.
The cotton bale is opened and its fibers are raked mechanically to remove foreign matter. A picker then wraps the fibers into a lap. A carding machine brushes the loose fibers into rows that are joined as a soft continuous nonwoven sheet, or web, and forms them into loose untwisted rope known as card sliver. For higher quality yarn, the sliver is put through a combing machine, which strengthens the fibers to a finer degree. In the drawing stage, rollers reduce the sliver to a uniform strand of a usable size. The drawing stage is also commonly referred to as the drafting stage. Even thinner strands may be produced by pulling and slightly twisting the sliver. Finally, the sliver is transferred to a spinning frame, where it is drawn further, and wound on a bobbin as yarn.
However, the drawing process to reduce the sliver to a usable size, and then the pulling on the sliver to reduce the sliver further, are time and space consuming steps of the yarn making process. Eliminating the drawing and the pulling of the sliver would create a faster, more efficient, yarn making process.
Therefore, there is a need for an apparatus and process for dividing a continuous, nonwoven web from the carding machine into a plurality of continuous ribbons. The present invention must forego the drawing and pulling of the web into a sliver, but permit the ribbons to be manufactured according to desired widths with a uniform linear density.
The present invention solves the above-identified problems by providing an apparatus and process for dividing a continuous web into a plurality of continuous ribbons. The present invention utilizes differences in travel distance of different portions of the continuous web to achieve fiber parallelization and repetition. The difference in travel distance between portions of the continuous web is achieved by creating a velocity differential between adjacent portions of the web over a fixed period of time.
Generally described, the present invention includes an apparatus for providing a plurality of continuous ribbons from a continuous nonwoven web. The apparatus includes an assembly of converging belts. At least two pairs of converging belts lie longitudinally adjacent to one another. Each pair of converging belts cooperate to receive and grip the incoming continuous web. At least one pair of converging belts varies the speed of one portion of the continuous web relative to another adjacent portion of the continuous web driven by the other pair of converging belts. Because adjacent portions of the continuous web are driven at different speeds, the continuous web is divided in a longitudinal manner into two continuous ribbons of desired width.
According to one aspect of the invention, a wheel sized to facilitate shearing engages and places pressure on each pair of converging belts. Because the belts are then urged against the continuous web, the continuous web is gripped by the belts.
According to another aspect of the invention, a pair of pressure pads persuades a pair of converging belts against the continuous web. The pressure pads are laterally spaced from one another and substantially coextensive. The pressure pads are moveable with respect to one another to permit the pair of belts to pass therebetween.